DNA methylation was assessed using the Illumina HumanMethylation450 (“450k”) microarray, which measures CpG methylation across >485,000 probes covering 99% of RefSeq gene promoters17. Arrays were run following the manufacturer’s protocols. A percentage of the samples were run in duplicate across multiple processing plates to assess technical variability related to DNA extraction and bisulfite conversion. A total of 675 microarrays were scanned on 534 unique subjects – however, note that all analysis utilized only a single microarray from each sample (see below).
